Surgical probes of that kind are basically known and serve for example for tissue ablation or coagulation. For that purpose the shaft with the two electrodes is inserted into body tissue. For example a high-frequency ac voltage is applied to the two electrodes, and that causes an alternating current in the body tissue surrounding the shaft and causes it to be heated. The high-frequency current and the electrode geometry are so selected in that case that the heating of the body tissue which occurs as a consequence of the high-frequency current results in cell death and thus tissue sclerosis. It is possible in that way to treat for example tumors.
In order better to distribute the energy which is introduced into the body tissue and to prevent for example body tissue in the proximity of the electrodes from almost burning while scarcely any heat is still being produced at just a short distance from the electrodes, it is known for the electrodes to be cooled during delivery of the high-frequency current or heated to provide for ablation of the puncture passage. As cooling is particularly effective where the electrical field strengths are particularly high, it is possible in that way for heating of the body tissue to be more uniformly distributed to a greater volume.
The desire to be able to provide for temperature control of the electrodes involves further problems in regard to the structure of the shaft of the surgical probe. On the one hand the cooling liquid can be conducting (for example physiological saline solution) so that the cooling liquid can result in short-circuits between the two electrodes in the interior of the shaft. On the other hand the fluid passage for the cooling fluid requires a hollow electrode structure so that, with the shaft being of a small diameter which is also desired at the same time, it is only with difficulty that all demands in terms of mechanical strength and sealing integrity of the shaft can be met. That is especially the case insofar as the shaft of the surgical probe is usually inserted into the body tissue for treating same.
The known approaches for equally well satisfying all demands on a fluid-temperature-controlled surgical probe for interstitial thermotherapy are for the most part not totally satisfactory. Therefore the object of the invention is to provide a surgical probe which has good cooling properties, which has good electrical properties, which enjoys high mechanical strength and which in addition affords sealing integrity at high fluid pressures.